The present invention relates to wireless telecommunications services, and more particularly to capturing or modifying mobile subscriber information such as location information, as indicated by Serving MSCID, and cell and sector location, and other information, such as original dialed digits and subscriber profile, for use by service applications.
Wireless Prepaid Service (WPS) is an offering by wireless service providers that allows a subscriber to charge airtime and other fees against a positive balance in the subscriber""s account. Periodically, the subscriber replenishes the account balance so as to allow further service usage which may incur charges, such as airtime, voice messaging, etc. If the subscriber""s account balance drops below a certain threshold, further calls are not allowed, and in certain arrangements, in-process calls are terminated.
One system for delivering wireless prepaid services in an Integrated Services Digital Network User Part (ISUP) network is based on U.S. Pat. No. 5,377,186 to Wegner, et al., and also on U.S. patent application 09/020,351, filed Feb. 9, 1998, assigned to the assignee of the present invention, both of which are herein incorporated by reference. The system uses ISUP loop-around trunks to connect a Mobile Switching Center (MSC) to a WPS Service Control Point (SCP), where the WPS airtime usage and other charges are tracked. All signaling for calls originating from or terminating to a WPS subscriber are routed through the WPS SCP.
All WPS systems are designed to track airtime usage and charges for WPS subscriber calls originating in the subscriber""s home service area. However, current WPS systems using ISUP loop-around trunks or WPS point solutions connected to an MSC do not have the ability to determine and track roaming charges based on a roaming WPS subscriber""s Serving MSC (SMSC). The primary reason for the inability to charge variable roaming rates based on a WPS roamer""s location is that the common signaling protocols used to communicate between the MSC and the WPS product, such as ISUP, do not support parameters for Mobil Switching Center ID (MSCID), cell and sector.
One possible technique to determine a variable roaming rate for calls originating from a WPS roamer would be for each provider to assign a unique xe2x80x9c800xe2x80x9d backhaul number to each out-of-area SMSC in the network. Since calls originating from a roamer are almost always backhauled from the SMSC to an MSC in the subscriber""s home network, a WPS roaming rate based on the unique SMSC backhaul number could be determined. The problem with this technique is that it uses a large number of scarce network resources, in the form of xe2x80x9c800xe2x80x9d and other directory numbers, that could better be used to serve revenue generating customers.
It is the primary object of the present invention to provide a system and method to capture Serving MSCID and cell and sector within the Serving MSC area for roaming wireless subscribers, and make this information available to service applications, such as wireless prepaid service. It is a further object of the invention to implement the method without requiring programming logic changes to established network elements, including Home Location Registers (HLRs), Visitor Location Registers (VLRs) and MSCs. It is a further object of the invention to implement the method with optimal use of scarce network resources, such as xe2x80x9c800xe2x80x9d and other directory numbers.
The invention of applicants is based on inserting a network platform, referred to hereinafter as an xe2x80x9cIntercept Location Registerxe2x80x9d (ILR), into the signaling path between the HLR of the roaming subscriber and all SMSCs. The ILR performs its functions in a transparent manner from the perspectives of the HLR and the SMSC. The HLR and SMSC both think they are effectively communicating directly to each other following normal wireless intersystem operations.
By being in the signaling path between the HLR and SMSC, the ILR can perform certain unique functions. In particular, the ILR can save information present in the messages exchanged between the HLR and SMSC, such as the MSCID, cell and sector values included in the Registration message from the SMSC to the HLR for a roaming WPS subscriber, for subsequent use by a WPS SCP application for, for example, variable roaming rate determinations. The ILR can also modify messages exchanged between the HLR and SMSC to assist service applications.
In the preferred embodiment, the ILR sends messages it receives from SMSCs to the HLR and sends messages it receives from the HLR to SMSCs without significant modification, except for Registration Notification (REGNOT) and response (regnot) messages that are associated with WPS subscribers"" Mobile Identification Numbers (MINs), maintained in a WPS MIN database on the ILR. In all cases, the ILR modifies the Serving MSCID parameter in messages it receives from the SMSC to the HLR to point to the ILR, so that response messages from the HLR will be returned to the ILR rather than directly to the SMSC.
When the ILR receives a REGNOT message associated with a WPS subscriber from a SMSC, it stores the MSCID, cell and sector included in the REGNOT message and passes the message to the HLR. When the ILR receives the regnot response message from the HLR, the regnot message is modified to include a hotline directory number (DN) that directs all calls originated by the roaming subscriber to be backhauled through the subscriber""s Home MSC (HMSC), or an equivalent MSC that has ISUP loop-around trunks, which enable the call""s ISUP signaling to be passed through the WPS SCP.
When subsequent calls are originated by or terminated to the roaming WPS subscriber, the subscriber""s Serving MSCID and cell and sector that are stored in the ILR can be accessed by the WPS SCP application for variable roaming rate determination.
This technique can be used for roaming subscribers in home or foreign networks.